Alkoxyalkyl esters of iodo-alkoxy substituted phenyl acetic acids



Patented Apr; 17, 1951 ALKOX ALKYL ESTERSOF 'IoDo-ALK'oXY 4 SUBSTITUTED PHENYL ACETIC ACIDS Sydney Archer, Albany, N. Y., assignor to Stcrling 1 Drug Inc., New York, N. Y.,- a corporationof Delaware No Drawing.

- *This invention relates to alkoxyalkyl esters of iodo-lower-alk oxyphenylacetic acids and to their preparation.

My new compounds are opaque to X-rays and are therefore valuableas contrast media in the jroentgenological examination of body cavities, I for which urpose they can be administered directlyintothe cavity to be outlined.

Ifhave round that these substances are .ofparticular value in the roentgenological examination of the spinal chord andsub-arachnoid space, i. e., in that branch of radiography known as myelography. An ideal "myelograph'ic agent is one which is easily and rapidly administered and may be distributed readily .and evenly to Various parts of the cerebrospinal system, without, however,

for myelography include gases, such as air'and oxygen, thorium dioxide sols, iodized oils and, more recently, a product consisting of a mixture of ethyl esters of isomeric iodophenylundecylic acids. vantages. Gases, although good contrast media, are dificult to administer properly, since their fluid, a procedure which can result in dangerous complications. Thorium dioxide sols lack the objectionable qualities of gases but have been found to cause untoward reactions, as well as imposing the possibility of eventual injury from residual radioactivity. Iodized and brominized oils, such asiodiz ed poppyseed oil, iodized sesame oil, iodized rapeseed oil, and brominized olive oil, are effective contrast agents and non-toxic, but are largely 11nsatisfactory because of their high viscosity, and slightly-irritatin properties. They must be injected under pressure and after examination be withdrawn by aspiration, for otherwise they remain largely unabsorbed for aperiod of years and may result in cicatrix formation due to prolonged Each of these agents has certain disad-- Serial No. 73,-663

Application January 29, 1949;

12 Claims. (01. ,260--- -4="73) radiopaque mediaasmyelographic agents'has been investigated, these compound have been found unsatisfactoryfor a number of reasons. Diifusion is too rapid, .and the compound becomes diluted with the spinal fluid, thereby losing its radiopacity unless a large quantity is injected, whereupon toxicity becomes amajor factor, as the substance is then rapidly absorbed intothe circulatory system.

phenylacetic acids have many advantages over the above-described .myelographic agents. They are much more readily eliminated from-the organism Without mechanicalmeans, being completely absorbed from the spinal-canal in a matter of days as compared to months or years 'with difiusing so rapidly thatthe radiopacity is lost. "It hould be eliminated readily, preferably without mechanical means, and .be of low toxicity and tolerated in other ways by thepatient.

Up to the present time,the various agents used use requires removal of part of the cerebrospinal compounds ranges media now in :general use.- The esters of my invention have the further advantage of being pure compounds instead of a mixture of isomers, and have in general a greaterradiopacity than the old iodized oils, due to a. higher percentage ofiodine, particularly amonglower members of the series. The new compounds also cause little or no irritation of animal meiribranesand are relatively nonli l y compounds have the general formula I I V v g omc oo-Y-o-o-a' no wherein R and R are lower alkyl groups and Y is a lower alkylene radical. By a lower alkyl group I mean one having preferably six carbon atoms or less. The total carbon contentof my from 12 to about 16 carbon atoms. 7 j

They are synthesized by esterification of an iodoalkoxyphenylacetic acid with an alkoxyalkanoleither by directinteraction of the twosubstances or by closely related reactions which are described below. The intermediate iodoalkoxye phenylacetic acids maybe prepared by various methods commonly used for introduction of iodine into an aromatic ring. If a compound is desired where the iodine *islin t-he orltho or para position with respect to the alko'xygroup, direct iodination of an alkoxyphenylacetic acid may be "employed. If the iodine is not to be ortho or para to the alkoxy group, indirect methods must be used such as replacement of an amino group by iodine (Sandmeyer reaction) in an aniinoalkoxyphenylacetic :acid; V

The alkoxyiodophenylacetic acid, may be esterified "by one of the following methods: (1), the acid and'analkoxyalkanol are combined di- The alkoxyalkyl esters of iodo-lower-alkoxyrectly optionally in the presence of an acid catalyst? (2), said acid in the form of a reactive derivative, such as the acid halide or anhydride, is reacted with an alkoxyalkanol; or (3), a metallic salt of said acid is reacted with an alkoxyalkyl halide.

Examples of intermediate acids which may be thoroughly extracted with ether.

used in my invention include 3-iodo-4-methoxy- H phenylacetic acid, 2-iodo-5-methoxyphenylacetic acid, 3-iodo-6-methoxyphenylacetic acid, 3-iodo- After removal of the ether the residual oil was distilled. The fraction boiling at 173-175 C. (0.6 mm.) was redistilled to give 11 g. of 2-ethoxyethyl 3-iodo-4-methoxyphenylacetate, B. P. 172- 5-methoxyphenylacetic acid, 3--'-iodo 4 ethoxy phenylacetic acid, 3-iodo-4-propoxyphenylacetic acid, 2-iodo-5-ethoxyphenylacetic acid, 2-iodo-5- propoxyphenylacetic acid, etc.

Examples of the intermediate alcohols which may be used include 2-methoxyethanol, 2-ethoxyethanol, 2-n-propoxyethanol, 2-isopropox'yethanol, 2-n-butoxyethanol, 3-methoxypropanol, 3-

, ethoxypropanol, 3-n-propoxypropanol, 3'-isopropoxypropanol, 3 n butoxypropanol, 4 methoxybutanol, 4-ethoxybutanol, etc.

The above-named alcohols when esterifled by the methods described using some of the acids named above give compounds within the scope of my invention including such species as 2-methoxyethyl 3 iodo 4 methoxyphenylacetate, 2 methoxyethyl 2 iodo-5-methoxyphenylacetate, 2-

propoxyethyl 3-i0do6-methoxyphenylacetate, 2-

isopropoxyethyl 3-iodo-5-methoxyphenylacetate, Z-butyloxyethyl 3-iodo-4-methoxyphenylacetate, 3-methoxypropyl 3-iodo 4 methoxyphenylacetate, 3-ethoxypropyl 3-iodo 4 methoxyphenylacetate, 3isopropoxypropyl 3-iodo 4- methoxyphenylacetate, 3-butbxypropyl 3-iodo 4 methoxyphenylacetate, 4 methoxybutyl 3 iodo 4 methoxyphenylacetate, 2 ethoxyethyl 3-iodo-4- propoxyphenylacetate, Z-ethoxyethyl 2 iodo 5 ethoxyphenylacetate and 2-ethoxyethyl 2-iodo- 5-propoxyphenylacetate.

The following examples will illustrate my invention more fully but should not represent a limitation in the scope thereof.

EXAMPLE 1 (a) 3-iodo-4-methoxyphenylacetic acid A solution of 30 g. of p-methoxy-phenylacetic acid in 140 ml. of 50% acetic acid was heated to 80 C., and a solution of 12 ml. of iodine monochloride in 12 ml. of acetic acid was added dropwise. Heating was continued at 80 C. for one hour, and the mixture was poured into about 500 (b) Z-ethozcyethyl 3-iodo-4-methoaryphenylacetate A mixture of 22 g. of 3-iodo-4-methoxyphenylacetic acid and 50 ml. of thionyl chloride was heated gently at reflux temperature for 90 minutes. The excess thionyl chloride was then removed in vacuo, and 50 ml. of beta-ethoxyethanol 175 C. (0.5 mm.); nn =1.5572; viscosity (25C.) =50.3 cs.

Anal.-Caled. for C13H11IO4: C, 42.88; H, 4.71; I, 34.86. Found: C, 42.80; H, 4.98; I, 35.47.

EXAMPLE 2 Z-methoxyethyl 3-iodo-4-methomyphenylacetate cmoQoracooomornoon,

A mixture of 30 g. of 3-iodo-4methoxyphenylacetic acid and 150 ml. of beta-methoxyethanol was refluxed for about 15 hours. The mixture was then poured into ice-water and thoroughly extracted with ether. The ether extracts were washed with dilute sodium carbonate solution, then with water and dried. After removal of the ether the residual oil was fractionated at reduced pressure to give 9.8 g. of Z-methoxyethyl 3-iodo- 4-methoxyphenylacetate, B. P. 167-169 C. (0.6 mm); viscosity (25 C.) 56.2 cs.

AnaZ.-Calcd. for C12 H16IO4; C, 41.04; H, 4.27; I, 36.14. Found: C, 41.32; H, 4.35; I, 36.50.

EXAIHPLE 3 (a) 2-iodo-5-methomyphenylacetic acid A solution of 230 g. of m-methoxyphenylacetic acid in 720 ml. of acetic acid and 720 ml. of water was heated to C. Then a solution of 324. g. of iodine monochloride in ml. of acetic acid was added dropwise over a period of one-half hour. The mixture was kept at this temperature for two hours and then allowed to stand at room temperature for two days. It was then warmed to redissolve the solid which had separated and was treated with sulfur dioxide in order to decolorize the solution. The resulting solution was cooled, and'the solid which separated was collected by filtration. A recrystallization of this solid from ethyl alcohol gave a first crop of 178 g., M. P. 123-124 C. and a second crop of 75 g., M. P. 119-123 C. The two crops were combined and recrystallized from a benzene-petroleum ether mixture, giving 220 g. of 2-iodo-5-methoxyphenylacetic acid, M. P. 127-130 C. An analytical sample was obtained by further recrystallization from ethyl alcohol and melted at 129-130 C.

AnaZ.Calcd. for CsHtIOsZ I, 43.45. Found: I, 43.50.

(b) Z-methoxgrethyl 2-iodo-5-methomyphenyl-' acetate @cmooocmomoom on.

A mixture of 30 g. of 2-iodo-5-methoxyphenylacetic acid, ml. of 2-methoxyethanol and 2 ml. of concentrated sulfuric acid was refluxed for about fifteen hours. The mixture was then poured into ice water and thoroughly extracted with ether. The ether extracts were washed with dilute'sodium carbonate solution, then with water and dried. After removal of the ether the residual oil was fractionated at reduced pressure giv- EXAMPLE 4 Z-ethoscyethyl. 2.-iodo--metho:cyphenylacetate @0310 0 0 omen, o C'HzCHc A, mixture of 30 g. of 2-iodo-5-methoxyphenylacetic acid, 156 ml. of 2-ethoxyethanol and '2 ml. of concentrated sulfuric. acid was refluxed for about' fifteen hours. The mixture was. then poured into. ice water and thoroughly extracted with ether. The ether extracts were washed with dilute sodium carbonate solution, then with water and dried. After removal of the ether the residual oil was fractionated at reduced pressure. The fraction boiling at 161-195 C. (0.5 mm.) was redistilled giving 16.7 g. of Z-ethoxyethyl 2-iodo-5-methoxyphenylacetate, B. P. 166-168 C. (0.6 mm); n =l.5636; viscosity (25 C.) =45.9 cs.

AnaZ.Calcd. for C12H15IO4: C, 41.16; H, 4.31; I, 36.24. Found: C, 41.40; H, 4.56; I, 36.45.

I claim:

1. Beta-ethoxyethyl 3-iodo-4-methoxyphenylacetate having the formula I eHao- 3-emeooememoomei1 2. Beta-ethoxyethyl 2-iodo-5-methoxyphenylacetate having the formula I Game 00 ememo omen, CHQJ) 3. Beta-methoxyethyl 2-iodo-5-methoxyphenylacetate having the formula Demo 0 0 011101120 0H3 4. A compound of the formula Demo 0 o-Y-oR' R0 containing a total of from 12-16 carbon atoms, wherein R and R are lower-alkyl groups and Y is a lower-alkylene radical in which at least :2 carbon atoms separate the carboxyl groupffrom the OR group.

5. A compound of the formula I RQ-OemeOO-Y-O R 6 containmga total affront. 1.2-1ficarbon atoms. wherein R and R are lower-alkyi; groups and Y' is a Iower-alkylene radical in which at least 2 carbon atoms separate the carboxyl. group from the OR group.

'7. A compound of the formula Q-emeoo-Y-oaz c Hs 7 containing a total of from 12-16 carbon. atoms. wherein R is a lower-alkyl group and Y is a lower-alkylene radical in which at least 2 carbon atoms separate the carboxyl group, from the OR group.

8. A compound of the. formula containing a total of from 12-16 carbon atoms, wherein R is a lower-alkyl group and Y is a lower-alkylene group in which at least 2 carbon atoms separate the carboxyl group from the OR group.

9. A process of preparing a compound of the formula Demo O0-Y-O R containing a total of from 12-16 carbon atoms, wherein R and R are lower-alkyl groups and Y is a lower-alkylene radical in which at least 2 carbon atoms separate the carboxyl group from the OR group, which comprises reacting a member of the group consisting of an acid of the formula Demo OOH the acid halide of said acid and the acid anhydride of said acid with a lower-alkoxyalkanol.

10. A process of preparing a compound of the formula containing a total of from 12-16 carbon atoms, wherein R and R are lower-alkyl groups and Y is a lower-alkyene radical in which at least 2 carbon atoms separate the carboxyl group from the OR group, which comprises reacting the acid halide of an acid of the formula Demo 00H with a lower-alkoxyalkanol.

11. A process of preparing a compound of the formula Demo oo-Y-o R containing a total of from 12-16 carbon atoms, wherein R and R are lower-alkyl groups and 7 Y is a lower-alkylene radical in which at least 2 carbon atoms separate the carboxyl group from the OR group, which comprises reacting an acid of the formula with a lower-alkoxyalkanol in the presence of a mineral acid catalyst.

12. A process of preparing a compound of the formula containing a total of from 12-16 carbon atoms, wherein R and R are lower-alkyl groups and Y is a lower-alkylene radical in which at least 20 2 carbon atoms separate the carboxyl group from the OR group, which comprises reacting a metallic'salt of an acid of the formula DQ111000 R0 with a lower-alkoxyalkyl halide.

SYDNEY ARCHER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,400,433 Natelson et a1 May 14, 1946 FOREIGN PATENTS Number Country Date 517,382 Great Britain July 25, 1939 517,425 Great Britain Jan. 30, 1940 OTHER REFERENCES ODonnell et al.: J; A. C. S., v01. 68, p. 1865 (1946). 

4. A COMPOUND OF THE FORMULA 